Abstract
Abstract Influenza infection cause human morbidity and death worldwide in every year. Infectous human influenza virus is major formed by influenza A virus. High pathogenic avian influenza viruses perhaps cause outbreak of pandemic, recently. According to World Health Organization estimates, the mortality of H5N1 in humans is greater than 60%. Over the past 60 years, vaccination has been the most effective method to protect the population against avian influenza virus infection. Hemagglutinin (HA), a glycoprotein on the surface of influenza virus, is responsible for major receptor binding to human cells, and mainly as a target for vaccine development. Chinese Hamster Ovary cells (CHO) and dihydrofolate reductase (dhfr)/methotrexate (MTX) gene amplification system are commonly used in biopharmaceutical industry to generate stable expressing recombinant proteins CHO cell clones. In this study, I expressed the optimizing H5HA protein coding sequence conjugated with GCN4 in CHO cells to produce secreted recombinant HA proteins. During gene amplification, we used dhfr-targeting RNA silencing vector (sd2) and Herpes simplex virus thymidine kinase weak promoter (pHSV-TK-driven dhfr) to weaken DHFR expression for improvement of high producer CHO cell clones selection. The high producer cell clones with sd2 and pHSV-TK-driven dhfr would be selected and could be used for mass producing recombinant HA glycoprotein subunit vaccine. These studies suggest that the incorporation of psd2 silencing vector with either strong or weak promoter vectors were better than the use of weak promoter vector only.